The invention relates to biodurable polycarbonate polyurethanes and biocompatible devices made therefrom.
Pinchuk U.S. Pat. No. 4,739,013 discloses polyurethanes which are reaction products of a polycarbonate macroglycol, a diisocyanate, and a polyfunctional poly(fluoroalkylsiloxane) having hydrolytically unstable Si--O--C moieties resulting from the reaction of a silanol-terminated monomer with a glycol 4:41-55!.
Kira et al. U.S. Pat. No. 4,834,746 discloses poly(alkoxy) block copolymers with internal siloxane segments mixed with polyurethanes and polyurethaneureas for making artificial vessels 1:19-21, 3:35!. Poly(alkoxy) block copolymers contain numerous biologically unstable ether linkages. See also Ward et al. U.S. Pat. No. 4,686,137 (describing a block copolymer of polyethyleneoxide, urethane, siloxane, and polytetramethylene oxide, as a coating or film which contains numerous biologically unstable ether linkages 5:5-10, 4:31, 4:36!).
Ward et al. U.S. Pat. No. 5,589,563 discloses medical devices made of a base polymer covalently bonded to a polysiloxane-terminated polycarbonate aliphatic polyurethane, less than 5% by weight relative to the base polymer, including 1,3-cyclohexyl diamine and ethylene diamine as chain extenders FIGS. 5 and 6, 5:64-66, 13:55-57!. Ward '563 does not teach internal siloxane segments. In fact, Ward '563 teaches that the surface-modifying moieties are preferably at the termini of the base polymer 6:55-64!. Ward '563 also teaches that silicones are resistant to oxidative degradation 9:9-10!. Example 1 uses a diethylamine terminator.
Ward et al. U.S. Pat. No. 4,675,361 discloses physical mixtures of base polymers such as polyurethanes and polycarbonates 5:35-45! with block copolymers of poly(dialkyl)-siloxanes for medical devices that contact blood 9:63-65, 2:20!. These devices have only a small percentage of the siloxane polymer additive.
Ward et al. U.S. Pat. No. 4,861,830 discloses a crosslinked, thermoset polysiloxane-polyurethane useful for surfaces which contact blood. Ward '830 teaches that silicone-containing polycarbonates have low contact angles which may be inappropriate for a blood-contacting surface 1:65-2:2!.